The invention relates to a process for the preparation of an olefin polymerization catalyst component comprising a magnesium dihalide, a titanium tetrahalide, and a dicarboxylic acid di-, oligo- and/or polyester as internal electron donor. The invention also relates to such a catalyst component and its use for the polymerization of xcex1-olefins such as propene.
Generally, so called Ziegler-Natta catalyst components of the above kind have been prepared by reacting a magnesium halide-alcohol complex support with a titanium tetrahalide and an electron donor which usually is a phthalic acid di-, oligo- or polyester. The preparation involves the use of large amounts of reagents and washing liquids, which are difficult to handle. Additionally, byproducts are formed, which cannot easily be regenerated or destroyed, but form an environmental problem.
For example, the preparation of a conventional polypropene catalyst component involves the reaction of a magnesium dichloride-alcohol complex support with titanium tetrachloride to give a reactive xcex2-magnesium dichloride surface as intermediate and hydrogen chloride and titanium alkoxy trichloride as byproducts. Then, the reactive xcex2-magnesium dichloride surface is activated with further titanium tetrachloride to give said catalyst component (the treatment with a titanium halide such as titanium tetrachloride is henceforth called titanation). This gives an inert magnesium chloride-based support covered with active sites based on titanium, chlorine and, optionally, an internal electron donor.
The titanium alkoxy trichloride byproduct formed in said titanation is a catalyst poison and must be carefully removed by extensive washing using large amounts of titanium tetrachloride. Further, the titanium alkoxy trichloride must be carefully separated from the titanium tetrachloride washing liquid, if the latter is to be reused e.g. for activating the reactive xcex2-magnesium dichloride. Finally, the titanium alkoxy trichloride is a hazardous waste material, which is difficult to dispose of.
Thus, in a typical propene polymerization catalyst component preparation involving two titanations and three heptane washes, one mol of produced catalyst component (mol Mg) requires about 40 mol of titanium tetrachloride e.g. as washing liquid to be circulated, and produces as waste material an amount of about three mol of titanium alkoxy trichloride as well as about three mol of hydrogen chloride.
Sumitomo, EP 0 748 820 A1 (hereinafter referred to as xe2x80x9cSumitomoxe2x80x9d), has prepared dialkoxy magnesium, reacted it with titanium tetrachloride to form an intermediate and then reacted the intermediate with phthalic acid dichloride to form a catalytically active propene polymerization catalyst component. The activity was raised by repeated titanations, as well as repeated washes with toluene and hexane. See page 10, lines 14 to 37, of said publication.
Said process of Sumitomo has avoided the reaction between the solid magnesium dichloride-alcohol complex and liquid titanium tetrachloride, and thereby eliminated the formation of large quantities of catalytically poisonous titanium alkoxy trichloride byproduct. However, as much as four titanations and hydrocarbon treatments are still needed to give satisfactory catalytic activity.
Further, conventional processes based on titanium trichloride and on titanium tetrachloride covered magnesium dichloride give catalyst component particles of either the wrong size or too broad a particle size distribution. As the relative size and size distribution of the catalyst component particles are reproduced in the olefin polymer (the so called xe2x80x9creplicationxe2x80x9d-phenomena), this is reflected as morphology problems in the polymer product. Such problems are, e.g., fouling of the polymerization reactor and clogging of its piping due to the presence of too much fines.
The purpose of the present invention is to provide a process which results in a catalyst component having satisfactory activity without producing harmful byproducts such as said titanium alkoxy trichloride or requiring the use of large amounts of titanation reagent and/or washing liquid. A further purpose of the invention is to obtain a catalyst component which has the right particle size and size distribution, so that a suitable polymer will be obtained without disturbances in the polymerization process.
The problem described above has now been solved with a novel process for the preparation of a catalyst component of the above type, which is mainly characterized by the steps of:
(i) reacting in solution at least one magnesium compound (a), selected from the group consisting of a dialkyl magnesium R2Mg, an alkyl magnesium alkoxide RMgOR, wherein each R is a similar or different C1-C20 alkyl, and a magnesium dihalide MgX2, wherein X is a halogen, with at least one alcohol (b), selected from the group consisting of a mixture of at least one monohydric alcohol Rxe2x80x2OH and at least one polyhydric alcohol Rxe2x80x2(OH)m, and at least one polyhydric alcohol Rxe2x80x2(OH)m, wherein Rxe2x80x2 is an 1-valent or, respectively, an m-valent C1-C20 hydrocarbyl group and m is an integer selected from 2, 3, 4, 5 and 6, to give a first intermediate (ab), and
(ii) reacting in solution said first intermediate (ab) with at least one dicarboxylic acid dihalide (c) which forms essentially all of said carboxylic acid di-, oligo- and/or polyester and has the formula (1): 
xe2x80x83wherein each Rxe2x80x3 is a similar or different C1-C20 hydrocarbyl group or both Rxe2x80x3:s form together with the two unsaturated carbons of the formula a C5-C20 aliphatic or aromatic ring, and Xxe2x80x2 is a halogen, to give a second intermediate (abc), and
(iii) reacting said second intermediate (abc) with at least one titanium tetrahalide TiXxe2x80x34 (d) wherein Xxe2x80x3 is a halogen,
(iv) recovering by precipitation said catalyst component in crude form, or a precursor of said catalyst component, and
(v) optionally washing said crude catalyst component or said precursor, to give said catalyst component.
It has thus been found that a high activity olefin polymerization catalyst comprising a magnesium halide, a titanium tetrahalide and a dicarboxylic acid di-, oligo- and/or polyester as internal donor can be prepared without the above mentioned disadvantages by reacting the reaction product of a dialkyl magnesium or a magnesium halide and a polyhydric alcohol with a dicarboxylic acid dihalide and a titanium tetrahalide. Further, by means of the polyhydric alcohol, the morphology of the catalyst component and thus the morphology of the polymer can be controlled and improved.
Of the above mentioned steps (i) to (iii), preferably all are performed in solution. If necessary, one or several hydrocarbon solvents, optionally with the application of stirring and/or heating, can be used to dissolve the reactants. Performing the process in a solution means that all reagent molecules have access to, and can react with, each other, thus forming a homogenous reaction product. Earlier processes which have been performed by reacting a solid support with a titanium compound and an electron donor, do not form this kind of homogenous reaction products. See the above description of earlier technique.
The catalyst component is in step (iv) preferably recovered in solid form by precipitation. Precipitation in the present invention means that the reaction product formed in solution is recovered as a powder, the particles of which comprise similar individual molecules of that reaction product. It is thus distinguished from earlier processes which include first the precipitation of a support and then the reaction of the support surface with catalytically active component(s). The particles formed according to the present invention are thus homogenous, while the particles of earlier processes are more or less heterogenous (inert core+active surface).
It is preferable if said first and second intermediates as well as the final product of the claimed process are separate compounds with an essentially stoichiometric composition. Often, they are complexes. A complex is, according to Rxc3x6mpps Chemie-Lexicon, 7. Edition, Franckh""sche Verlagshandlung, W. Keller and Co., Stuttgart, 1973, page 1831, xe2x80x9da derived name of compounds of higher order, which originate from the combination of molecules,xe2x80x94unlike compounds of first order, in the creation of which atoms participate.
The process according to the present invention starts with step (i), in which a dialkyl magnesium or a magnesium dihalide is reacted with a polyhydric alcohol Rxe2x80x2(OH)m or a mixture thereof with a monohydric alcohol Rxe2x80x2OH. The use of a polyhydric alcohol Rxe2x80x2(OH)m improves both the activity and the morphology of the catalyst component compared to the use of a monohydric alcohol alone. It is also possible to react all magnesium compounds (a) separately with a monohydric alcohol or a polyhydric alcohol, or a mixture of them. In the formulas, each Rxe2x80x2 can be the same or different.
Typical polyhydric alcohols are ethylene glycol, propylene glycol, trimethylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 2,3-butylene glycol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, pinacol, diethylene glycol, triethylene glycol, glycerol, trimethylol propane and pentareythritol. The polyhydric alcohol can be selected on the basis of the activity and morphology it gives the catalyst component. Thus, for example, ethylene glycol gives a high activity catalyst component, large polymer (PP) particles and a broad polymer particle size distribution. Compared to ethylene glycol, 2-butyl-2-ethyl-1,3-propanediol gives a moderate activity, small polymer particles and a very narrow polymer particle size distribution.
According to one embodiment of the present invention, the polyhydric alcohol has the formula Rxe2x80x2(OH)m, wherein Rxe2x80x2 is a di-, tri- or tetravalent C2-C16 alkyl group and m is an integer selected from 2, 3, 4, 5 and 6. Preferably, Rxe2x80x2 is a divalent or a trivalent C2-C16 alkyl group and m is an integer selected from 2 and 3. Most preferably the polyhydric alcohol is selected from the group consisting of ethylene glycol and 2-butyl-2-ethyl- 1,3-propanediol. By valence is understood the number of bonds that an atom can form (Stanley H. Pine, Organic Chemistry, 5. edition, McGraw-Hill, Inc., New York, 1987, page 10).
The amount of polyhydric alcohol may vary a lot, depending on the used amounts of magnesium compound (a), dicarboxylic acid dihalide (c) and the reactive halogenated hydrocarbon (e) described below. While the polyhydric alcohol certainly reacts with the magnesium compound, it may also be involved in reaction with the dicarboxylic acid dihalide (c), and/or even with the reactive halogenated hydrocarbon (e) described below. According to a preferred embodiment, said magnesium compound (a) is in step (i) reacted with said polyhydric alcohol Rxe2x80x2(OH)m in a molar ratio Mg/Rxe2x80x2(OH)m of between 1:1 and 1:0.25, preferably between about 1:0.8 and about 1:0.3.
Even better results are obtained if in step (i), said magnesium compound (a) is reacted with at least two of said alcohols (b). It is preferable to use as said at least one alcohol (b) a mixture of at least one monohydric alcohol Rxe2x80x2OH and at least one polyhydric alcohol Rxe2x80x2(OH)m.
According to an embodiment of the invention, said magnesium compound (a) is reacted separately with at least one monohydric alcohol Rxe2x80x2OH and at least one polyhydric alcohol Rxe2x80x2(OH)m. The intermediate solutions obtained are further reacted with said at least one dicarboxylic acid dihalide. These solutions are then mixed and the mixture is reacted with said at least one titanium tetrahalide.
Typical C1-C5 monohydric alcohols are methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec.butanol, tert.butanol, n-amyl alcohol, iso-amyl alcohol, sec.amyl alcohol, tert.amyl alcohol, diethyl carbinol, akt.amyl alcohol, sec.isoamyl alcohol, tert.butyl carbinol. Typical C6-C10 monohydric alcohols are hexanol, 2-ethyl-1-butanol, 4-methyl-2-pentanol, 1-heptanol, 2-heptanol, 4-heptanol, 2,4-dimethyl-3-pentanol, 1-octanol, 2-octanol, 2-ethyl-1-hexanol, 1-nonanol, 5-nonanol, diisobutyl carbinol, 1-decanol and 2 ,7-dimethyl-2-octanol. Typical  greater than C10 monohydric alcohols are n-1-undecanol, n-1-dodecanol, n-1-tridecanol, n-1-tetradecanol, n-1-pentadecanol, 1-hexadecanol, n-1-heptadecanol and n-1-octadecanol. The monohydric alcohols may be unsaturated, as long as they do not act as catalyst poisons.
Preferable monohydric alcohols are those of formula Rxe2x80x2OH in which Rxe2x80x2 is a C2-C16 alkyl group, most preferably a C4-C12 alkyl group, like 2-ethyl-1-hexanol.
The quality and quantity of monohydric alcohol relative to the amount of magnesium compound (a) may vary a lot, depending on the used quality and quantity of polyhydric alcohol, magnesium compound (a), dicarboxylic acid dihalide (c) and reactive halogenated hydrocarbon (e). The molar ratio Mg/Rxe2x80x2OH is preferably between about 1:5 and about 1:1, more preferably between about 1:4 and about 1:1, most preferably between about 1:2.5 and about 1:1.5.
The dialkyl magnesium (a) used in step (i) has the formula R2Mg or RMgOR, wherein each one of the two R:s is a similar or different C1-C20 alkyl, preferably a similar or different C4-C12 alkyl. Typical magnesium alkyls are ethylbutyl magnesium, dibutyl magnesium, dipropy magnesium, propylbutyl magnesium, dipentyl magnesium, butylpentylmagnesium, butyloctyl magnesium and dioctyl magnesium. Typical alkyl-alkoxy magnesium compounds are ethyl magnesium butoxide, magnesium dibutoxide, butyl magnesium pentoxide, magnesium dipentoxide, octyl magnesium butoxide and octyl magnesium octoxide. Most preferably, one R of the suitable formula R2Mg is a butyl group and the other R is an octyl group, i.e. the dialkyl magnesium compound is butyl octyl magnesium. When used as said magnesium compound (a), the preferred magnesium dihalide is magnesium dichloride MgCl2.
It is also possible to used both a magnesium dihalide and a dialkyl magnesium for example as follows:
MgCl2+4ROHxe2x86x92MgCl2xc2x74ROH
MgCl2xc2x74ROH+2MgRxe2x80x2xe2x80x32xe2x86x92MgCl2[Mg(OR)2]2+4Rxe2x80x2xe2x80x3H
The reaction conditions used in step (i) of the claimed process may be varied according to the used reactants and agents. The conditions should be adjusted to give sufficiently of said reaction product (ab) between the magnesium compound (a) and said alcohol(s) (b). According to an embodiment of the present invention, said magnesium compound (a) is reacted with said at least one alcohol (b), under at least one of the following conditions:
at raised temperature, preferably at about 30xc2x0 C. to about 80xc2x0 C.,
for a period of about 10 min to about 90 min, preferably about 30 min,
in the presence of a C5-C10 hydrocarbon solvent, preferably heptane.
In addition to the above embodiments of step (i), other variations and reactions may also be used to produce said first intermediate (ab), still being within the present scope of protection. Thus, with respect to step (i), the scope of protection should be interpreted under the doctrine of equivalence on the basis of what a skilled person could have done to achieve said first intermediate (ab).
According the invention, the product of step (i), or a similar composition, i.e. said first intermediate (ab), is in a succeeding step (ii) reacted with a dicarboxylic acid dihalide (c) of the formula (1) to give a second intermediate (abc), and said second intermediate (abc) is in a third step (iii) reacted with a titanium tetrahalide TiXxe2x80x34 (d) wherein Xxe2x80x3 is a halogen.
The formula (1) of the dicarboxylic acid dihalide is: 
wherein each Rxe2x80x3 is a similar or different C1-C20 hydrocarbyl group or both Rxe2x80x3:s form together with the two unsaturated carbons seen in the formula a C5-C20 aliphatic or aromatic ring, and Xxe2x80x2 is a halogen.
Among non-cyclic dicarboxylic acid dihalides, the group consisting of maleic acid dihalide, fumaric acid dihalide and their Rxe2x80x3 substituted derivatives such as citraconic acid dihalide and mesaconic acid dihalide, respectively, are the most important. As the invention aims at converting the dicarboxylic acid dihalides into their corresponding di-, oligo- or polyesters, and the di-, oligo- or polyesters as internal electron donors have to be coordinable with the magnesium dihalide and the titanium tetrahalide of the catalyst component, the cis-isomeric maleic acid dihalide and its derivatives, such as citraconic acid dihalide, are more advantageous.
However, in order to obtain a catalyst with exceptionally high activity, the Rxe2x80x3:s of formula (1) should form together with the two unsaturated carbons seen in the formula a C5-C20 aliphatic or aromatic ring. Among the cyclic dicarboxylic acid dihalides, the group consisting of phthalic acid dihalide (1,2-benzene dicarboxylic acid dihalide), its hydrogenate 1,2-cyclohexane dicarboxylic acid diahlide, and their derivatives, is the most important. Most preferably, said dicarboxylic acid dihalide (c) is phthaloyl dichloride.
The amount of the dicarboxylic acid dihalide (c) may vary a lot, depending on the amount of alcohol (b) used in step (i) and the amount of alkoxide present in said first intermediate (ab). It is within the scope of protection of the present patent to adjust the amounts in order to react said intermediate with said dicarboxylic acid dihalide. According to a preferred embodiment of the present invention, in step (ii), said first intermediate (ab) is reacted with said dicarboxylic acid halide (c) in a molar ratio Mgtotal added/(c) of between 1:1 and 1:0.1, preferably between about 1:0.6 and about 1:0.25.
The reaction conditions of step (ii) of the claimed process may vary according to the used components and their amounts. However, they should be adjusted to give sufficiently of said reaction product (abc) between said intermediate (ab) and said dicarboxylic acid dihalide (c). According to an embodiment of the present invention, in step (ii), said first intermediate (ab) is reacted with said dicarboxylic acid dihalide (c), under at least one of the following conditions:
adding said dicarboxylic acid dihalide (c) under room temperature and heating the obtained reaction mixture,
keeping the reactants together at raised temperature, preferably at about 30xc2x0 C. to about 80xc2x0 C.,
keeping the reactants together for a period of about 10 min to about 90 min, preferably about 30 min,
reacting the reactants in the presence of a C5-C10 hydrocarbon solvent, preferably heptane.
Usually, a C5-C10 hydrocarbon solvent is used in step (ii). Then, it is preferable, that, after said first intermediate (ab) has been reacted with said dicarboxylic acid dihalide (c), the C5-C10 hydrocarbon solvent is removed by evaporation, e.g. that heptane is used and removed at about 100xc2x0 C. to about 110xc2x0 C.
In the invention, it was found that the addition of at least one reactive halogenated hydrocarbon (e) during the process, i.e. in any of the above steps (i) to (iii), led to a further improved catalytic activity. The reactive halogenated hydrocarbon (e) has the formula (2)
Rxe2x80x2xe2x80x3Xxe2x80x2xe2x80x3nxe2x80x83xe2x80x83(2)
wherein Rxe2x80x2xe2x80x3 is an n-valent C1-C20 hydrocarbyl group, Xxe2x80x2xe2x80x3 is a halogen and n is an integer selected from 1, 2, 3 and 4.
Such chlorinated hydrocarbons are, e.g., monochloromethane, dichloromethane, trichloromethane (chloroform), tetrachloromethane, monochloroethane, 1,1-dichloroethane, 1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,2-trichloroethane, 1,1,1,2-tetrachloroethane, 1,1,2,2-tetrachloroethane, pentachloroethane, hexachloro-ethane, 1-chloropropane, 2-chloropropane, 1,2-dichloropropane, 1,3-dichloro-propane, 1,2,3-trichloropropane, 1-chlorobutane, 2-chlorobutane, isobutyl chloride, tert.butyl chloride, 1,4-dichlorobutane, 1-chloropentane, 1,5-dichloropentane. The chlorinated hydrocarbons of the invention may also be unsaturated, provided that the unsaturation does not act as catalyst poison in the final catalyst component.
In said reactive halogenated hydrocarbon (e) having the above formula (2), Rxe2x80x2xe2x80x3 is preferably a mono-or bivalent C1-C10 hydrocarbyl group, independently, Xxe2x80x2xe2x80x3 is preferably chlorine and, independently, n is preferably 1 or 2. Preferably said hydrocarbyl halide (e) is a butyl chloride (BuCl) or a dichloroalkane like 1,4-dichlorobutane, more preferably tertiary butyl chloride or a dichloroalkane like 1,4-dichlorobutane, most preferably a dichloroalkane like 1,4-dichlorobutane.
It was also found, that especially good results were obtained, if said reactive halogenated hydrocarbon (e) is added in an amount corresponding to a molar ratio Mgtotal added/(e) of between 1:0.2 and 1:20, preferably between about 1:1 and about 1:4.
Said reactive halogenated hydrocarbon (e) can be added in any of steps (i) to (iii). Preferably it is added in connection with step (ii). This means that in the process, it is preferably added immediately before the dicarboxylic acid dihalide (c), together with it or immediately after it. As there is a possibility that the reactive halogenated hydrocarbon (e) may disturbe the conversion of the dicarboxylic acid dihalide into said dicarboxylic acid di-, oligo- and/or polyester donor, it is most preferably added immediately after the addition of the dicarboxylic acid dihalide (c). The symbols (ab) and (abc) may or may not include the added or reacted reactive halogenated hydrocarbon (e). The symbols do not limit the reactants leading to the corresponding intermediates to (a), (b), (c) and (d).
As was said above, it is preferable to add said reactive halogenated hydrocarbon (e) in connection with and preferably after the dicarboxylic acid dihalide (c), i.e. at the end of step (ii). Most preferably, after said preferable C5-C10 hydrocarbon solvent, such as heptane, has been removed by evaporation after step (ii), said second intermediate (abc) is contacted with said reactive halogenated hydrocarbon (e). A convenient contacting period is about 10 min to about 90 min, preferably about 30 min.
In the reaction sequence (i)xe2x86x92(ii)xe2x86x92(iii), after said second intermediate (abc) has been contacted with said reactive halogenated hydrocarbon (e), preferable in step (ii), a dissolving C5-C10 hydrocarbon, such as toluene, is preferably added. Without limiting the scope of patent protection, the hydrocarbon is believed to dissolve the reaction product and/or the lower the viscosity of its solution, thus making the intermediate (abc, including (e)) more available for reaction with the titanium tetrahalide TiXxe2x80x34 (d) in the succeeding step (iii). Most preferably molar ratio Mgtotal added/toluene of between about 1:2 and about 1:10 is used in the addition.
In step (iii), the magnesium compound/alcohol/dicarboxylic acid dihalide reaction product (abc) is reacted with at least one titanium tetrahalide TiXxe2x80x34 (d), wherein Xxe2x80x3 is a halogen. Equivalent with said titanium tetrahalide is the combination of an alkoxy titanium halide and a halogenation agent thereof, which are able to form a titanium tetrahalide in situ. However, the most preferred titanium tetrahalide (d) is titanium tetrachloride.
The amount of titanium tetrahalide may vary a lot and depends e.g. on the manner of contacting it with said intermediate (abc). If the titanium tetrahalide is added to the intermediate, a large stoichiometric excess thereof is not needed. If, however, the intermediate, or solution thereof, are added e.g. dropwise to the titanium tetrahalide, a large stoichiometric excess of the last mentioned is preferred. Within the scope of the claimed process, the amount of titanium tetrahalide may be optimized to give a suitable catalyst. Most preferably, in step (iii), said second intermediate (abc) is added into and reacted with said titanium tetrahalide (d) in a molar ratio Mgtotal added/(d) of between 1:100 and 1:1, preferably between about 1:50 and about 1:5, most preferably about 1:10.
As was said before, both order of contacting between said intermediate (abc) and said titanium tetrahalide give satisfactory results and may be applied to the present invention. When using the reaction sequence (i)xe2x86x92(iii), it is preferable if in step (iii), said second intermediate (abc), more preferably a solution thereof, is added slowly, most preferably dropwise, to said titanium tetrahalide (d) to form a solution of said catalyst component. Thereby, the titanium tetrahalide is preferably hot, most preferably at 110xc2x0 C. The best results are obtained, if in step (iii), a toluene solution of said second intermediate (abc) is added dropwise to said titanium tetrahalide (d) at 110xc2x0 C. The corresponding reaction time is preferably about 5 min to about 20 min, most preferably about 10 min.
After the reaction sequences (i)xe2x86x92(ii)xe2x86x92(iii), the reaction product, which is a precursor of, or a crude version of said catalyst component, is recovered in a recovery step (iv). The reaction product is preferably recovered by continuously heating a solution of said catalyst component, most preferably said toluene solution of said catalyst component, for the precipitation of the catalyst component in crude form or as said precursor and allowing it to settle. Immediately before said precipitation, preferably a C5-C10 hydrocarbon solvent, more preferably toluene, most preferably toluene in a molar ratio Mgtotal added/toluene of about 1:10 to about 1:100, is added to said catalyst component solution. After the crude catalyst component or said precursor has settled, the supernatant liquid is removed e.g. by decantering or siphoning.
After the recovery step (iv), said catalyst component in crude form or said precursor is optionally washed in a washing step (v). By precursor is meant a reaction product, which still is not in the form of the final catalyst component. This state of thing derives from the nature of the reaction product, which may be a larger complex (see definition above) or mixture consisting of or containing one or several molecules and/or smaller complexes. Because of the loose structure of such a larger complex or complex mixture, washing will remove some of the complexes and/or molecules and essentially change the composition of the remaining solid product.
It is preferable if, in step (v), said recovered catalyst component in crude form or said catalyst component precursor is washed with toluene, preferably with hot (e.g. 90xc2x0 C.) toluene. It is further preferable, if in step (v), said recovered crude catalyst component, said recovered precursor or said preliminary washed catalyst component is washed with heptane, most preferably with hot (e.g. 90xc2x0 C.) heptane. Yet further, it is preferable, if in step (v), said recovered crude catalyst component, said recovered precursor or said preliminary washed catalyst component is washed with pentane. A washing step (v) typically includes several substeps which gradually increase the magnesium dihalide content of the catalyst precursor. Such a washing sequence is, for example, one wash with toluene at 90xc2x0 C., two washes with heptane at 90xc2x0 C. and one wash with pentane at room temperature.
The washing can according to the invention be optimized to give a catalyst with novel and desirable properties. Thus in step (v) said recovered catalyst component is preferably washed to give the following ratio of said magnesium dihalide, said titanium tetrahalide, and said dicarboxylic acid di-, oligo- and/or polyester as internal electron donor ED (3):
(MgX2)8-10(TiXxe2x80x34)1(ED)0.7-1.3 xe2x80x83xe2x80x83(3)
wherein MgX2 is said magnesium dihalide, TiXxe2x80x34 is said titanium tetrahalide, and ED is said dicarboxylic acid di-, oligo- and/or polyester as internal electron donor, preferably a phthalic acid di-, oligo- or polyester. X and Xxe2x80x3 are preferably Cl.
Finally, the washed catalyst component is usually dried, preferably by evaporation.
In appendices 1 and 2 are described the schemes of eight (sixteen) embodiments of the present invention; four (eight) starting from a magnesium dihalide MgX2 and four (eight) starting from a dialkyl magnesium R2Mg.
In addition to the above described process, the invention also relates to an olefin polymerization catalyst component comprising a magnesium dihalide, a titanium tetrahalide, and a dicarboxylic acid ester as internal electron donor ED, which has been prepared according to the above described process. By said catalyst component is meant the so called procatalyst component, i.e. the transition metal component of the whole olefin catalyst system, which catalyst system additionally includes a so called cocatalyst, i.e. an organic compound of a non-transition metal, and optionally a so called external electron donor.
An advantageous embodiment of the catalyst component according to the present invention comprises a magnesium dihalide, a titanium tetrahalide, and a dicarboxyl acid ester as internal electron donor ED and has the following ratio of said magnesium dihalide, said titanium tetrahalide, and said dicarboxylic acid ester as internal electron donor ED (3):
(MgX2)8-10(TiXxe2x80x34)1(ED)0.7-1.3xe2x80x83xe2x80x83(3)
wherein MgX2 is said magnesium dihalide, TiXxe2x80x34 is said titanium tetrahalide and ED is said dicarboxylic acid ester as internal electron donor, preferably a phthalic acid di-, oligo- or polyester. Especially, this applies for X=Xxe2x80x3=Cl. This composition gives the highest activity. Preferably, the catalyst component is a complex having the formula (3).
When using a polyol Rxe2x80x2(OH)m, wherein Rxe2x80x2 is an m-valent C1-C20 hydrocarbyl group and m is an integer selected from 2, 3, 4, 5 and 6, according to the present invention, its morphology can conveniently be adjusted to give olefin polymers of various desired particle sizes and particle size distributions (PSD). As was said above, the polyhydric alcohol can be selected on the basis of the activity and morphology it gives to the catalyst component. Thus ethylene glycol gives a high activity catalyst component, large polymer (PP) particles and a broad polymer particle size distribution, whereas 2-butyl-2-ethyl-1,3-propanediol gives a moderate activity, small polymer particles and a very narrow particle size distribution.
When adding during the preparation process of the claimed catalyst component a reactive halogenated hydrocarbon (e) of the formula (2)
Rxe2x80x2xe2x80x3(Xxe2x80x2xe2x80x3)nxe2x80x83xe2x80x83(2)
wherein Rxe2x80x2xe2x80x3 is an n-valent C1-C20 hydrocarbyl group, Xxe2x80x2xe2x80x3 is a halogen and n is an integer selected from 1, 2, 3 and 4, the product will preferably contain more halogen than was to be expected on the basis of the MgX2 and TiX4 present. Preferably, when the halogen is chlorine, the claimed catalyst component might contain chlorine from about 10% to about 60% more than the amount of chlorine calculated on the basis of the amounts of magnesium and titanium present, assuming that all of the magnesium is in the form of said MgCl2 and essentially all of the titanium is in the form of said TiCl4.
In the claimed catalyst component, the magnesium halide (X=Cl) structure has an X-ray diffraction pattern which differs from the X-ray diffraction pattern of pure MgCl2. It preferably shows an X-ray diffraction pattern with a lamellar thickness indicating peak at 17xc2x0 2"THgr", showing a clear position shift compared to normal amorphous MgCl2 which gives a height indicating peak at 15xc2x0 2"THgr". Indeed, according to J. Dorrepaal et al. (J. Appl. Crystallography, 1984 17, page 483), the crystal structure of MgCl2 is characterized by a=3,640 xc3x85 and C=17,673 xc3x85. In an X-ray diffraction pattern the peak at about 15xc2x0 2"THgr" is in the direction (003) of the c-axis, i.e. describing the height to the hexagonal unit cell, when Cu Kxcex1 radiation is used.
In addition to the above described process and catalyst component, the invention also relates to a process for the polymerization of olefins. The process is characterized by the steps of
(A) preparing in solution an olefin catalyst component by
(i) reacting at least one magnesium compound (a), selected from the group consisting of a dialkyl magnesium R2Mg, wherein each R is a similar or different C1-C20 alkyl, and a magnesium dihalide MgX2, wherein X is a halogen, with at least one alcohol (b), selected from the group consisting of a mixture of at least one monohydric alcohol Rxe2x80x2OH and at least one polyhydric alcohol Rxe2x80x2(OH)m, and at least one polyhydric alcohol Rxe2x80x2(OH)m, wherein Rxe2x80x2 is an 1-valent or, respectively, an m-valent C1-C20 hydrocarbyl group and m is an integer selected from 2, 3, 4, 5 and 6, to give a first intermediate (ab), and
(ii) reacting said first intermediate (ab) with at least one dicarboxylic acid dihalide (c) which forms essentially all of the dicarboxylic acid di-, oligo- and/or polyester and has the formula (1): 
xe2x80x83wherein each Rxe2x80x3 is a similar or different C1-C20 hydrocarbyl group or both Rxe2x80x3:s form together with the two unsaturated carbons of the formula a C5-C20 aliphatic or aromatic ring, and Xxe2x80x2 is a halogen, to give a second intermediate (abc), and
(iii) reacting said second intermediate (abc) with at least one titanium tetrahalide TiXxe2x80x34 (d) wherein Xxe2x80x3 is a halogen, or
(iixe2x80x2) reacting said first intermediate (ab) with at least one titanium tetrahalide TiXxe2x80x34 (d) wherein Xxe2x80x3 is a halogen, to give an alternative second intermediate (abd), and
(iiixe2x80x2) reacting said alternative second intermediate (abd) with at least one dicarboxylic acid dihalide (c) which forms essentially all of the dicarboxylic acid di-, oligo- and/or polyester and has the formula (1): 
xe2x80x83wherein each Rxe2x80x3 is a similar or different C1-C20 hydrocarbyl group or both Rxe2x80x3:s form together with the two unsaturated carbons of the formula a C5-C20 aliphatic or aromatic ring, and Xxe2x80x2 is a halogen,
(iv) recovering by precipitation said catalyst component in crude form, or a precursor of said catalyst component, and
(v) optionally washing said crude catalyst component or said precursor, to give said catalyst component,
(B) feeding to at least one polymerization reactor said catalyst component, as well as a cocatalyst, which has the formula (4)
RpAlrX3rxe2x88x92pxe2x80x83xe2x80x83(4)
xe2x80x83wherein R is a C1-C10 alkyl, preferably a C1-C4 alkyl, most preferably ethyl, X is a halogen, preferably chlorine, p is an integer from 1 to (3rxe2x88x921), preferably 2 or 3, most preferably 3, and r is 1 or 2, preferably 1, the molar ratio between said catalyst component and said cocatalyst, expressed as Al/Ti, preferably being 10-2000, more preferably 50-1000, most preferably 200-500,
optionally an external electron donor, which preferably is a silane, more preferably a C1-C12 alkyl-C1-C12 alkoxy silane, most preferably cyclohexyl methyl dimethoxy silane,
optionally a C4-C10 hydrocarbon solvent, preferably pentane, hexane and/or heptane,
preferably a chain transfer agent, which is hydrogen, and
at least one olefin monomer, which preferably is propylene,
(C) carrying out the polymerization of said olefin monomer in said at least one polymerization reactor to give an olefin polymer (=homopolymer or copolymer) and
(D) recovering said olefin polymer.
In the claimed olefin polymerization process, the used (transition metal) catalyst component can be prepared according to any above described embodiment of the catalyst component preparation process.
According to one further embodiment of the invention, olefins are polymerized by the steps of
(A) providing a solid olefin polymerization catalyst component which is essentially homogenous and comprises a magnesium dihalide, a titanium tetrahalide, and a dicarboxylic acid di-, oligo- and/or polyester as internal electron donor ED in the following ratio (3):
(MgX2)8-10(TiXxe2x80x34)1(ED)0.7-1.3xe2x80x83xe2x80x83(3)
xe2x80x83wherein MgX2 is said magnesium dihalide, TiXxe2x80x34 is said titanium tetrahalide, X and/or Xxe2x80x3 is preferably Cl, and ED is said dicarboxylic acid di-, oligo- and/or polyester as internal donor, preferably a phthalic acid di-, oligo- or polyester,
(B) feeding to at least one polymerization reactor said catalyst component, as well as a cocatalyst which has the formula (4)
RpAlrX3rxe2x88x92p xe2x80x83xe2x80x83(4)
xe2x80x83wherein R is is a C1-C10 alkyl, preferably a C1-C4 alkyl, most preferably ethyl, X is a halogen, preferably chlorine, p is an integer from 1 to (3rxe2x88x921), preferably 2 or 3, most preferably 3, and r is 1 or 2, preferably 1, the molar ratio between said catalyst component and said cocatalyst, expressed as Al/Ti, preferably being 10-2000, more preferably 50-1000, most preferably 200-500,
optionally an external electron donor, which preferably is a silane, more preferably a C1-C12 alkyl-C1-C12 alkoxy silane, most preferably cyclohexyl methyl dimethoxy silane,
optionally a C4-C10 hydrocarbon solvent, preferably pentane, hexane and/or heptane,
preferably a chain transfer agent, which is hydrogen, and
at least one olefin monomer, which preferably is propylene,
(C) carrying out the polymerization of said olefin monomer in said at least one polymerization reactor to give an olefin polymer (=homopolymer or copolymer) and
(D) recovering said olefin polymer.
The invention is described below by means of examples, the purpose of which merely is to illustrate the invention.